Defectivity in Silicon Nitride Etching with Phosphoric Acid using Single Wafer Processing

Single wafer cleaning processing can effectively address particle and defect issues commonly associated with conventional batch processing. However, phosphoric acid wet etching of silicon nitride (Si<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>) continues to rely on batch processing in semiconductor manufacturing. In this work, we assess single wafer processing for phosphoric acid etching, focusing on improved uniformity and defect reduction. We demonstrate that single wafer processing achieves within-wafer uniformity of less than 5 % at a high silicon nitride etching thickness of 600 Å. We discuss how defectivity increases with queue time and highlight the importance of optimizing rinsing steps for reducing defects.